In the presence of sunlight, Volatile Condensable Material (VCM) emitted from commonly used room temperature vulcanizing (RTV) material can photochemically deposit onto optically-sensitive spacecraft surfaces and significantly alter their original, beginning-oflife (BOL) optical properties, such as solar absorptance and emittance, causing un-intended performance loss of the spacecraft. We have employed in-situ spectroscopic ellipsometry to monitor in real time the condensed and photofixed effluent of RTV CV10-2568. This technique is sensitive to nm thick layers and can be used to extract n and k as a function of wavelength.